The present invention relates to a backlight device provided, for example, in a transmission type liquid crystal display (LCD) or the like, and to a radiator annexed to the backlight device.
The liquid crystal display is suitable for contriving a larger display screen, a lighter weight, a thinner shape, a lower power consumption and the like, as compared with the cathode ray tube (CRT). Therefore, liquid crystal displays have come to be used for TV sets and various displays, together with, for example, the self-light-emitting type PDPs (Plasma Display Panels) and the like. The liquid crystal display has a liquid crystal panel in which liquid crystals are sealed between two transparent substrates of various sizes, and the orientations of liquid crystal molecules are changed by impressing a voltage so as to change the light transmittance, thereby optically displaying a predetermined picture and the like.
Since the liquid crystal itself is not a light-emitting body, the liquid crystal display is provided with a backlight unit functioning as a light source at, for example, a back surface portion of the liquid crystal panel. The backlight unit includes, for example, a primary light source, a light guide plate, a reflective film, a lens sheet or diffusion film, and the like, and display light is supplied to the whole area of the liquid crystal panel. In the backlight unit, a cold cathode fluorescent lamp (CCFL) having mercury or xenon is sealed in a fluorescent tube has been used as the primary light source; however, there are problems yet to be solved, such as the problem of sufficient fluorescence luminance and life possessed by the cold cathode fluorescent lamp and the problem of the uniformity ratio of illuminance arising from the presence of a low luminance region on the cathode side.
Meanwhile, in a large-sized liquid crystal display, there is generally provided an area litconfiguration backlight device in which a plurality of long cold cathode fluorescent lamps are disposed on the back surface of a diffuser plate and which supplies display light to the liquid crystal panel. Also in such an area litconfiguration backlight device, there is a need to solve the problems of the cold cathode fluorescent lamp mentioned above, and, particularly in a large-type TV set exceeding 40 inches in size, the problems of obtaining a higher luminance and a higher uniformity ratio of illuminance are emphasized.
On the other hand, in the air litconfiguration backlight device, attention has been paid to the LED area litconfiguration backlight in which multiplicities of red, green and blue light emitting diodes (LEDs) are arranged two-dimensionally on the back side of a diffuser film to obtain white light, in place of the above-mentioned cold cathode fluorescent lamp. In the case of such an LED backlight device, a reduction in cost is contrived attendant on a reduction in the cost of LEDs, and a high-luminance picture and the like are displayed on a large-sized liquid crystal display with low power consumption.